1. Field
The following description relates to an active radio frequency identification (RFID) system, and more particularly, to a pseudo noise (PN) code generator according to International Standardization Organization/International Electrotechnical Commission (ISO/IEC) 24370-2 or 18185-5 type B.
2. Description of the Related Art
A radio frequency identification (RFID) system includes a reader, an antenna, and a tag and can be employed to recognize a person, a vehicle, a product, a transport card, and the like without touching the item to be recognized. REID systems can be categorized into active and passive types according to the presence of a signal oscillator in a tag. However, the categorization is generally based on whether a power supply, usually a battery, is present in a tag; with the active type requiring a battery and the passive type not requiring a battery. The active type RFID tag enables long-distance communication over several tens of meters.
A pseudo noise (PN) code generator is implemented in an RFID tag and an RFID reader. In a case where an additional transmitter is operated in order to achieve better performance, for example, to improve time synchronization, an additional PN code generator is required for the transmitter in addition to an existing PN code generator. In this case, a technical solution for generating a PN code having superior cross-correlation characteristic as well as a good autocorrelation characteristic is required.